我正在尝试使用jpa更新父实体和子实体（随父实体一起提供）。我试过很多方法，但都做不到。它给了我以下的错误。
javax.persistence.entityexistsexception:具有相同标识符值的不同对象已与会话联系人关联（6）
以下是实体，
父->user.java

@Entity
public class User extends Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "seq_generator")
    @SequenceGenerator(name = "seq_generator", sequenceName = "seq_users", initialValue = 1, allocationSize = 1)
    private Long id;

    private String firstName;
    private String lastName;
    private String email;
    private String password;
    private String street;
    private String city;

    @OneToOne(cascade = CascadeType.ALL, mappedBy = "userContact")
    private Contact contact;
}

子->contact.java

@Entity
public class Contact extends Serializable {

    private static final long serialVersionUID = 1L;

    @Getter(value = AccessLevel.NONE)
    @Setter(value = AccessLevel.NONE)
    @Id
    @Column(insertable = false, updatable = false)
    private Long id;

    @MapsId
    @OneToOne
    @JoinColumn(name = "id", nullable = false)
    private User userContact;

    private String phone;
}

在我的service.java中，我是这样更新的，

@Override
@Transactional
public User update(Long id, User user) {
    Optional<User> curUser = userRepo.findById(id);

    user.setId(curUser.get().getId());
    user.setStreet(curUser.get().getStreet());
    user.setCity(curUser.get().getCity());

    Contact contact = user.getContact();
    contact.setUserContact(user);

    user.setContact(contact);

    return userRepo.save(user);
}

更新json负载是这样的，

{
    "firstName": "FirstName",
    "lastName": "LastName",
    "email": "Email",
    "password": "Password",
    "contact": {
        "phone": "0123456789"
    }
}

为什么我不能马上更新？插入工作正常，但此更新不工作。我做错什么了？如果有人能帮我，我真的很感激。提前谢谢。
这是我尝试的新方法，

@Override
@Transactional
public User update(Long id, User user) {
    Optional<User> curUser = userRepo.findById(id);

    curUser.setFirstName(user.getFirstName());
    curUser.setlastName(user.getLastName());
    curUser.setEmail(user.getEmail());
    curUser.setPassword(user.getPassword());

    Contact contact = user.getContact();
    contact.setUserContact(curUser);

    curUser.setContact(contact);

    return userRepo.save(curUser);
}